Sean Buskirk, Ph.D.

Exploring the impact of genetic background on adaptive evolution

Abstract

Is evolution predictable? Forecasting of evolutionary outcomes first requires that evolution is repeatable. The question of repeatability in evolution was popularized by 20th century evolutionary biologist Stephen J. Gould when he asked if  “the tape of life could be replayed, would life look the way it does today?” While challenging, if not impossible, to conduct in natural populations, Gould's thought experiment has been brought to life in the laboratory in the form of experimental evolution. By initiating and propagating many replicate populations in a controlled environment, evolution can be “replayed” over and over. This research will  combine experimental evolution with comparative genomics and transcriptomics to investigate how genetic background effects adaptation to a common selective pressure. Diverse strains of the bacterial pathogen Staphylococcus aureus will be repeatedly exposed to ethanol, selecting for ethanol tolerant mutants. By identifying the genetic mechanisms of adaptation and their impact on gene expression, we can determine if closely-related bacteria adapt in similar ways or if adaptation is influenced by genetic background. Ultimately, this work will help to fill the gap in knowledge surrounding the role of genetic background in the ability to predict evolutionary outcomes.

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